A kinetic–equilibrium study of a triiodide concentration maximum formed by the persulfate–iodide reaction

Arthur E. Burgess, John C. Davidson

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The presence of triiodide, I3–, throughout the lifetime of a persulfate–iodide reaction with persulfate in excess, is controlled by an opposing effect of falling iodide concentration and rising iodine concentration. This brings triiodide to a concentration maximum, [I3–]max, which can be studied by UV–visible spectroscopy using absorbance measurements taken over an extended iodine clock time-scan. Equilibrium and conservation equations can be combined so that, together with [I3–]max, a value of the constant K for the equilibrium established between iodine, iodide, and the triiodide complex ion can be obtained.
Original languageEnglish
Pages (from-to)814–816
Number of pages3
JournalJournal of Chemical Education
Issue number6
Publication statusPublished - 2012
Externally publishedYes


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